Background The alkali metals and the alkaline earth metals by variablepitch333

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									Background: The alkali metals and the alkaline earth metals can both be identified with a
flame test. All of the alkali metals and some of the alkaline earth metals are so reactive
that they must be stored under oil in their pure form. A compound that contains the metal
will glow a specific color when placed into a flame. Each element absorbs a different
amount of energy so the electrons in the atom jump to a higher energy level. The atom is
unstable in this state to the electrons drop back to their original energy level releasing
energy. We see these releases of energy as different colors of light. Scientists use a
spectrum analyzer to study the spectral lines that it creates. Each element has its own
unique set of spectral lines that can identify that element.


Purpose:




Procedure:
   1. Prepare the data table.
   2. Wear safety goggles and a lab apron through out this activity.
   3. Light the Bunsen burner and adjust the flame so that you have a blue flame with a
      cone within a cone.
   4. Remove the wooden splint from the labeled test tube. Place the tip of the wooden
      splint in the inner cone of the flame. When you see the color, quickly remove the
      wooden splint from the flame to prevent burning. If you want to see the color
      again, you must dip the wooden splint into the solution again. Record the color
      you see in the table.
   5. Repeat the flame test ad look through the piece of cobalt blue glass. Record what
      you see.
   6. Replace the wooden splint back into the appropriate test tube and repeat with
      another solution.

Color options without using the cobalt blue glass

       Green                         Yellowish green
       Magenta Pink                  Orange
       Yellow-Purple                 Reddish orange
       Orange-yellow
Questions: Answer each question in a complete stand alone sentence.
   1. Why must you be careful to place the wooden splint back into the same test tube?
   2. Why must you quickly remove the wooden splint from the flame after you have
       identified the color?
   3. Is the flame test affected by the negative Nitrate ion? Explain how you know this.
   4. What were the colors of sample #8 (mixture of sodium and potassium) with and
       with out the cobalt blue glass?
   5. What colors does the cobalt blue glass filter out?
   6. What was the color of the flame for your unknown?
   7. What element (sample 1-7) is your unknown?
   8. What family are the alkali metals and why are they stored under oil?




Questions: Answer each question in a complete stand alone sentence.
   1. Why must you be careful to place the wooden splint back into the same test tube?
   2. Why must you quickly remove the wooden splint from the flame after you have
       identified the color?
   3. Is the flame test affected by the negative Nitrate ion? Explain how you know this.
   4. What were the colors of sample #8 (mixture of sodium and potassium) with and
       with out the cobalt blue glass?
   5. What colors does the cobalt blue glass filter out?
   6. What was the color of the flame for your unknown?
   7. What element (sample 1-7) is your unknown?
   8. What family are the alkali metals and why are they stored under oil?




Questions: Answer each question in a complete stand alone sentence.
   1. Why must you be careful to place the wooden splint back into the same test tube?
   2. Why must you quickly remove the wooden splint from the flame after you have
       identified the color?
   3. Is the flame test affected by the negative Nitrate ion? Explain how you know this.
   4. What were the colors of sample #8 (mixture of sodium and potassium) with and
       with out the cobalt blue glass?
   5. What colors does the cobalt blue glass filter out?
   6. What was the color of the flame for your unknown?
   7. What element (sample 1-7) is your unknown?
   8. What family are the alkali metals and why are they stored under oil?


Table

FlameTest: Data Table
Sample number   Solution              Color of Flame       Color of flame
                                      without the cobalt   looking through the
                                      blue glass           cobalt blue glass
1               Lithium Nitrate
                LiNO3
2               Sodium Nitrate
                NaNO3
3               Potassium Nitrate
                KNO3
4               Copper (II) Nitrate
                Cu(NO3)2
5               Strontium Nitrate
                Sr(NO3)2
6               Barium Nitrate
                Ba(NO3)2
7               Calcium Nitrate
                Ca(NO3)2
8               Unknown # ____

9               Unknown # ____

								
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